The ultimate goal of seismics is to find the physical properties of the subsurface. Seismic energy in the form of compressional or shear waves are transmitted into the ground and the reflections (echoes) from structures in the subsurface are recorded by sensors (hydrophones or geophones) most commonly located at, or near the surface of the earth.
The wave field recorded by the sensors is then processed in computers. The resulting xe2x80x9csound imagesxe2x80x9d of the subsurface are interpreted by geophysicists and geologists to make maps of the structures. These structures are mainly represented by interfaces separating layers with different physical properties. These interfaces are detectable only because they are capable of reflecting seismic energy.
This patent application describes a new method that estimates the reflectivity, expressed by the angle-dependant reflection coefficient, from seismic measurements.
There is a comprehensive literature on methods for estimating the reflectivity of reflectors in the subsurface. Such methods are often called xe2x80x9cTrue Amplitude Migration (TAM)xe2x80x9d methods. Within the scope of this patent application it is not possible to give a full review of all methods published, but a common feature of the existing methods is that they estimate both the spatial position and its reflectivity in one operation.
A review and comparison between several existing methods is found in [1] in the list of references. Important publications within TAM are [2], [3], [4], [5], [6] and [7].